UIThreadSynchronizer.java

/*******************************************************************************
 * Copyright (c) 2014 - 2017 Rüdiger Herrmann
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *   Rüdiger Herrmann - initial API and implementation
 ******************************************************************************/
package com.codeaffine.eclipse.swt.util;

import org.eclipse.swt.SWT;
import org.eclipse.swt.SWTException;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Widget;


public class UIThreadSynchronizer {

  public void asyncExec( Widget contextWidget, Runnable runnable ) {
    new UIThreadRunner( contextWidget ).asyncExec( runnable );
  }

  public void syncExec( Widget contextWidget, Runnable runnable ) {
    new UIThreadRunner( contextWidget ).syncExec( runnable );
  }

  private static class UIThreadRunner {
    private final Widget contextWidget;

    UIThreadRunner( Widget contextWidget ) {
      this.contextWidget = contextWidget;
    }

    void asyncExec( Runnable runnable ) {
      Display display = getDisplay();
      if( display != null ) {
        display.asyncExec( new GuardedRunnable( contextWidget, runnable ) );
      }
    }

    void syncExec( Runnable runnable ) {
      Display display = getDisplay();
      if( display != null ) {
        display.syncExec( new GuardedRunnable( contextWidget, runnable ) );
      }
    }

    private Display getDisplay() {
      Display result = null;
      if( !contextWidget.isDisposed() ) {
        result = safeGetDisplay();
      }
      return result;
    }

    private Display safeGetDisplay() {
      Display result = null;
      try {
        result = contextWidget.getDisplay();
      } catch( SWTException exception ) {
        handleSWTException( exception );
      }
      return result;
    }

    private static void handleSWTException( SWTException exception ) {
      if( exception.code != SWT.ERROR_WIDGET_DISPOSED ) {
        throw exception;
      }
    }
  }

  private static class GuardedRunnable implements Runnable {
    private final Widget contextWidget;
    private final Runnable runnable;

    GuardedRunnable( Widget contextWidget, Runnable runnable ) {
      this.contextWidget = contextWidget;
      this.runnable = runnable;
    }

    @Override
    public void run() {
      if( !contextWidget.isDisposed() ) {
        runnable.run();
      }
    }
  }

}